1. Field of the Invention
This invention relates to a manufacturing method for manufacturing filter elements for use in oil filters and air cleaners, etc., and more particularly relates to a method for rolling a roll filter paper.
2. Description of the Related Art
Cars are fitted with fuel filters for removing dirt from the fuel supplied to the engine.
The fuel filter is disposed, as shown in FIG. 22, in the fuel supply line 90 which supplies the fuel 6 to the engine. The fuel filter 9 is made up of a filter case 91, a cover 92 fitted to the top part of the filter case 91, and a filter element 1 contained inside the filter case 91. The fuel 6 enters the fuel filter 9 through an entry opening 920 centrally located in the cover 92, is filtered by the filter element 1, exits through an exit opening 930 centrally located in the base of the filter case 91, and is supplied to the engine (not shown in the drawings).
One example of a type of filter element used for the filter element 1 consists of a porous roll filter paper 10 of corrugated construction which has been rolled into a cylindrical shape, as shown in FIGS. 24-26 (Japanese Laid-Open Patent Publication No.H.4-131106).
The roll filter paper 10 is made up of two layers; a flat sheet 15 and a corrugated sheet 13. Hollow filter parts 14 are formed between the ridges 139 of the corrugated sheet 13 and the flat sheet 15. The troughs 131 of the corrugated sheet 13 are bonded to the flat sheet 15 by a sealant 2. The cavities formed by the corrugated sheet 13 other than the filter parts 14, in other words the cavities on the opposite side of the corrugated sheet 13 from the filter parts 14, are clean parts 16.
In each of the filter parts 14, as shown in FIGS. 22, 23 & 26, the inflow end 71 is open. The outflow end 79, however, is closed off by the ridges 139 of the corrugated sheet 13 being squeezed together with and joined to the flat sheet 15.
In each of the clean parts 16, on the other hand, the inflow end 71 is closed off by the sealant 2, and the outflow end 79 is open.
In this filter element 1, the fuel 6 enters the filter parts 14 through the inflow end 71 and passes through the porous roll filter paper 10 from the filter parts 14 into the clean parts 16. The dirt contained in the fuel 6 is trapped on the surface of the roll filter paper 10 on the filter part 14 side.
Filters similar to the filter element 1 discussed above are used in other filters, such as air filters and the like, as well as automobile fuel filters.
The method by which the filter element discussed above is manufactured will now be explained, with reference to FIG. 27.
First, the troughs 131 of a corrugated sheet 13 are bonded to a flat sheet 15, the ridges 139 of the corrugated sheet 13 at the outflow end 79 are squashed, and a long corrugated roll filter paper 10 is obtained. Then, the sealant 2 is applied to the inner surface of the roll filter paper 10 at the inflow end 71 side of the roll filter paper 10, in a narrow strip extending along the length of the roll filter paper 10 from the roll-start end 17. The roll filter paper 10 is then rolled up along its length, from the roll-start end 17 to the roll-finish end 19.
Conventionally this rolling operation is carried out by hand or using a rolling claw.
However, rolling by hand requires a lot of manpower and is time-consuming, and considerable practice is necessary in order to master the rolling operation.
When a rolling claw 30 is used to roll up the roll paper filter 10, the roll-start end of the roll paper filter 10 is gripped in the rolling claw 30, the sealant 2 is applied in a narrow strip along the inflow side 71, and after that the rolling claw 30 is rotated and the roll paper filter is rolled up. Howewer, in the process, as shown in FIG. 28, the sealant 2 gets onto the rolling claw 30, and this can result in it being impossible to remove the rolling claw 30 from the roll filter paper 10 on completion of rolling.